Polyethylene composition

ABSTRACT

A bimodal linear polyethylene composition, products made therefrom, methods of making and using same, and articles containing same.

FIELD

Polyethylene compositions, products, methods, and articles.

INTRODUCTION

Linear low density polyethylene (“LLDPE”) is compositionally distinctfrom low density polyethylene (“LDPE”) and has certain superiorproperties that have led it to replace LDPE in a number of commercialapplications. These include films, sheets, and injection moldedarticles. LLDPE films and sheets are used in packaging applications andnon-packaging applications. Examples are agricultural film, foodpackaging, garment bags, grocery bags, heavy-duty sacks, industrialsheeting, pallet and shrink wraps, and bags. LLDPE injection moldedarticles include buckets, freezer containers, lids, and toys.

Polyethylenes are mentioned in CA 2427685 A1; U.S. Pat. Nos. 7,576,166B2; 7,897,710 B2; 8,008,403 B2; 8,846,188 B2; 8,957,158 B2; 9,090,762B2; 9,284,389 B2; 9,309,338 B2; WO 2006/045738 A1; and WO 2015/069637A2.

U.S. Pat. No. 7,576,166 B2 to J. Äärllä et al. relates to a process forthe production of linear low-density polyethylene composition. A processfor producing bimodal linear low-density polyethylene polymercompositions, useful for making films. Exemplifies Ziegler-Nattacatalyst.

U.S. Pat. No. 8,846,188 B2 and U.S. Pat. No. 8,957,158 B2, both to F.Fantinel et al., relate to impact resistant LLDPE composition and filmsmade thereof. The polyethylene is produced in one gas phase reactor.

WO 2015/069637 A2 to A. M. Sukhadia relates to low density polyolefinresins with low molecular weight and high molecular weight components,and films made therefrom. Ethylene-based polymers produced using dualmetallocene catalyst systems.

SUMMARY

We recognized a problem that hurts the manufacturing, use, andperformance of prior LLDPEs made with metallocene catalyst (“priorMCN-LLDPE”). The problem also hurts the manufacturing, use, andperformance of prior blends comprising a prior LLDPE made withZiegler-Natta catalyst and the prior MCN-LLDPE. For example, relative toprocessability of prior LLDPEs made with Ziegler-Natta catalyst (“priorZN-LLDPE”), prior MCN-LLDPEs have inferior processability. For exampleduring extrusion of the prior MCN-LLDPE, the extruder barrel pressure ishigher than during extrusion of prior ZN-LLDPE. Also, prior MCN-LLDPEsmay have insufficient sealability (e.g., hot seal/hot tack may be tooweak) relative to prior ZN-LLDPE. Other processability drawbacks ofprior MCN-LLDPEs may include tan delta values that are too high,molecular weight distributions (MWD) that are too narrow, and shearthinning index values that are too low. Prior MCN-LLDPEs also may haveinsufficient stiffness or other mechanical properties that are notsufficient for certain applications. For example, for certain usesElmendorf tear in the cross direction (CD Tear) or machine direction (MDTear) may be too likely, melt strength may be too low, secant modulusmay be too low, and/or dart impact strength may be too low. The priorblend has dart impact property that is worse (lower) than that of theprior MCN-LLDPE alone. The more prior ZN-LLDPE that is mixed with theprior MCN-LLDPE, the worse the dart impact property of the blend gets.

A technical solution to this problem was not obvious from the prior art.A problem to be solved by inventiveness then is to discover a new LLDPEthat alone has at least one processability characteristic similar tothat of an unblended monomodal ZN-LLDPE and at least onestiffness/mechanical property similar to that of an unblended monomodalMCN-LLDPE.

Our technical solution to this problem includes a bimodal linear lowdensity polyethylene composition (“inventive bimodal LLDPE composition”)made with a bimodal catalyst system, products made therefrom, methods ofmaking and using same, and articles containing same. The inventivebimodal LLDPE composition has a combination of improved propertiescomprising at least one processability characteristic similar to that ofan unblended monomodal ZN-LLDPE and a dart impact property similar tothat of an unblended monomodal MCN-LLDPE. In some aspects the inventivebimodal LLDPE composition is characterized by a density from 0.9000 to0.9500 gram per cubic centimeter (g/cm³), alternatively from 0.9000 to<0.930 g/cm³, measured according to ASTM D792-13 Method B.

The inventive bimodal LLDPE composition may be characterized by at leastone improved property relative to that of a prior bimodal LLDPE.

The inventive bimodal LLDPE composition is useful in differentindustrial applications.

DRAWINGS

FIG. 1 contains drawings of structural formulas of (pro)catalysts.

FIGS. 2 and 3 are GPC chromatograms of inventive examples 1 and 2,respectively, of the inventive bimodal LLDPE composition.

DETAILED DESCRIPTION

The Summary and Abstract are incorporated here by reference.

Unpredictably, the inventive bimodal LLDPE composition has at least oneimproved property such as, for example, at least one improved(increased) processability property and/or at least one improved(increased) stiffness property. The improved processability property maybe at least one of decreased extruder barrel pressure, increasedsealability (e.g., hot seal/hot tack), decreased tan delta value, andincreased shear thinning index value. The improved stiffness propertymay be at least one of increased Elmendorf tear (CD Tear and/or MDTear), increased melt strength, increased secant modulus, and increaseddart impact strength. In some aspects the inventive bimodal LLDPEcomposition is not characterized by a worsening of any three,alternatively any two, alternatively any one of the foregoingproperties. The inventive bimodal LLDPE composition may be used to makefilms, sheets and injection molded articles.

Certain inventive embodiments are described below as numbered aspectsfor easy cross-referencing. Additional embodiments are describedelsewhere herein.

Aspect 1. A bimodal linear low density polyethylene compositioncomprising a lower molecular weight (LMW) polyethylene component and ahigher molecular weight (HMW) polyethylene component, wherein each ofthe LMW and HMW polyethylene components comprises ethylene-derivedmonomeric units and (C₃-C₂₀)alpha-olefin-derived comonomeric units; andwherein the bimodal linear low density polyethylene composition ischaracterized by each of limitations (a) to (c): (a) a resolvedbimodality (resolved molecular weight distribution) showing in achromatogram of gel permeation chromatography (GPC) of the bimodallinear low density polyethylene composition, wherein the chromatogramshows a peak representing the HMW polyethylene component, a peakrepresenting the LMW polyethylene component, and a local minimum in arange of Log(molecular weight) (“Log(MW)”) 1.5 to 5.0, alternatively 2.5to 5.0, alternatively 3.5 to 4.5, alternatively 4.0 to 4.5 (e.g.,Log(MW) is 4.05 to 4.25) between the peak representing the HMWpolyethylene component and the peak representing the LMW polyethylenecomponent, measured according to the Bimodality Test Method, describedlater; (b) a molecular mass dispersity (M_(w)/M_(n)), Ð_(M) (pronouncedD-stroke M), from 5 to 30.1, alternatively from 7 to 25, alternativelyfrom 10.1 to 20.1, all measured according to the Gel PermeationChromatography (GPC) Test Method, described later; and (c) nomeasurable, alternatively no detectable, amount of long chain branchingper 1,000 carbon atoms (“LCB Index”), measured according to LCB TestMethod (described later). The bimodal LLDPE composition may also becharacterized by limitation (d) a density from 0.9000 to 0.950 gram percubic centimeter (g/cm³).

Aspect 2. The bimodal LLDPE composition of aspect 1 described by any oneof limitations (i) to (vii): (i) a density from 0.9000 to less than (<)0.930 gram per cubic centimeter (g/cm³), alternatively 0.9000 to 0.9294g/cm³, alternatively 0.9000 to 0.9290 g/cm³, alternatively 0.9100 to0.9290 g/cm³, alternatively 0.9200 to 0.9290 g/cm³, all measuredaccording to ASTM D792-13 Method B; (ii) a melt index (190° C., 2.16kilograms (kg), “MI₂”) from 0.1 to 5.0 grams per 10 minutes (g/10 min.),alternatively 0.2 to 5.0 g/10 min., alternatively 0.5 to 3.0 g/10 min.,alternatively 0.5 to 2.0 g/10 min., alternatively from 0.5 to 1.5 g/10min., alternatively from 1.00 to 1.20 g/10 min., all measured accordingto the Melt Index MI₂ Test Method, described later; (iii) a tan delta(tan δ) from 5 to 35, alternatively from 5 to 25, alternatively from 5to 15, alternatively from 8 to 12, alternatively from 9 to 10, allmeasured at 190° C. and 0.1000 radians per second (rad/s) according toTan Delta Test Method, described later; (iv) both (i) and (ii); (v) both(i) and (iii); (vi) both (ii) and (iii); and (vii) each of (i), (ii),and (iii).

Aspect 3. The bimodal LLDPE composition of aspect 1 further described byany one of limitations (i) to (vii): (i) a density from 0.9000 to lessthan (<) 0.930 gram per cubic centimeter (g/cm³), alternatively 0.9000to 0.9294 g/cm³, alternatively 0.9000 to 0.9290 g/cm³, alternatively0.9100 to 0.9290 g/cm³, alternatively 0.9200 to 0.9290 g/cm³, allmeasured according to ASTM D792-13 Method B; (ii) a melt index (190° C.,2.16 kilograms (kg), “MI₂”) from 0.1 to 5.0 grams per 10 minutes (g/10min.), alternatively 0.2 to 5.0 g/10 min., alternatively 0.5 to 3.0 g/10min., alternatively 0.5 to 2.0 g/10 min., alternatively from 0.5 to 1.5g/10 min., alternatively from 1.00 to 1.20 g/10 min., all measuredaccording to the Melt Index MI₂ Test Method, described later; (iii) amolecular mass dispersity (M_(w)/M_(n)), Ð_(M), of at least one of theLMW and HMW polyethylene components of from >2.0 to <3.0, alternativelya M_(w)/M_(n) of the LMW polyethylene component from >2.0 to <3.0,alternatively a M_(w)/M_(n) of the LMW polyethylene component from >2.0to <3.0 and a M_(w)/M_(n) of the HMW polyethylene component from >3.0 to3.5, all measured according to the GPC Test Method, described later,after deconvoluting the LMW and HMW polyethylene components of thebimodal LLDPE composition according to the Deconvoluting Test Method,described later; (iv) both (i) and (ii); (v) both (i) and (iii); (vi)both (ii) and (iii); and (vii) each of (i), (ii), and (iii).

Aspect 4. The bimodal LLDPE composition of any one of aspects 1 to 3further described by any one of limitations (i) to (xii): (i) a flowindex (190° C., 21.6 kg, “FI₂₁”) from 4 to 500 g/10 min., alternativelyfrom 10 to 100 g/10 min., alternatively from 20 to 40 g/10 min.,alternatively from 31.0 to 34.0 g/10 min., all measured according to theFlow Index F1₂₁ Test Method, described later; (ii) a melt flow ratio(190° C., “MI₂₁/MI₂”) 20.0 to 50.0, alternatively from 24 to 39,alternatively from 25 to 35 and calculated according to the Melt FlowRatio Test Method, described later; (iii) a shear thinning index valuefrom 1.5 to 10, alternatively from 2.5 to 10.0, alternatively from 3.0to 10.0, alternatively from 3.1 to 5.0, measured according to the ShearThinning Index Test Method, described later; (iv) a number-averagemolecular weight (M_(n)) from 5,000 to 25,000 grams per mole (g/mol),alternatively from 7,000 to 20,001 g/mol, alternatively from 7,001 to15,000 g/mol, measured according to GPC Test Method, described later;(v) both (i) and (ii); (vi) both (i) and (iii); (vii) both (i) and (iv);(viii) both (ii) and (iii); (ix) both (ii) and (iv); (x) both (iii) and(iv); (xi) any three of (i) to (iv); and (xii) each of (i) to (iv).

Aspect 5. The bimodal LLDPE composition of any one of aspects 1 to 4further described by any one of limitations (i) to (iv): (i) the(C₃-C₂₀)alpha-olefin-derived comonomeric units are derived from1-butene; (ii) the (C₃-C₂₀)alpha-olefin-derived comonomeric units arederived from 1-hexene; (iii) the (C₃-C₂₀)alpha-olefin-derivedcomonomeric units are derived from 1-octene; and (iv) the(C₃-C₂₀)alpha-olefin-derived comonomeric units are derived from acombination of any two, alternatively each of 1-butene, 1-hexene, and1-octene.

Aspect 6. A bimodal linear low density polyethylene composition made bycopolymerizing ethylene (monomer) and at least one (C₃-C₂₀)alpha-olefin(comonomer) with a mixture of a bimodal catalyst system and a trimsolution in the presence of molecular hydrogen gas (H₂) and an inertcondensing agent (ICA) in one, two or more polymerization reactors(e.g., one fluidized bed gas phase reactor) under (co)polymerizingconditions; wherein prior to being mixed together the trim solutionconsists essentially of a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complex(procatalyst, e.g.,(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl) and an inert liquid solvent (e.g., liquid alkane) and thebimodal catalyst system consists essentially of an activator species(derivative, e.g., a methylaluminoxane species), abis(2-pentamethylphenylamido)ethyl)amine zirconium complex and a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumcomplex, all disposed on a solid support (e.g., a hydrophobic fumedsilica); and wherein the (co)polymerizing conditions comprise a reactiontemperature from 80 degrees (°) to 110° Celsius (C.), alternatively 83°to 106° C., alternatively 83° to 87° C., alternatively 91° to 100° C.,alternatively 101° to 106° C.; a molar ratio of the molecular hydrogengas to the ethylene (H2/C2 molar ratio) from 0.001 to 0.050,alternatively 0.001 to 0.030, alternatively 0.002 to 0.025,alternatively 0.010 to 0.020; and a molar ratio of the comonomer (Comer)to the ethylene (Comer/C2 molar ratio) from 0.005 to 0.10, alternatively0.008 to 0.050, alternatively 0.010 to 0.040. The bimodal LLDPEcomposition may be that of any one of aspects 1 to 5.

Aspect 7. A method of making a bimodal linear low density polyethylenecomposition, the method comprising contacting ethylene (monomer) and atleast one (C₃-C₂₀)alpha-olefin (comonomer) with a mixture of a bimodalcatalyst system and a trim solution in the presence of molecularhydrogen gas (H₂) and an inert condensing agent (ICA) in one, two ormore polymerization reactors under (co)polymerizing conditions, therebymaking the bimodal linear low density polyethylene composition; whereinprior to being mixed together the trim solution consists essentially ofa (tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumcomplex (procatalyst, e.g.,(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl) and an inert liquid solvent (e.g., liquid alkane) and thebimodal catalyst system consists essentially of a non-metalloceneligand-Group 4 metal complex (e.g., abis(2-pentamethylphenylamido)ethyl)amine zirconium complex) and ametallocene ligand-Group 4 metal complex (e.g., a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumcomplex), all disposed on a solid support (e.g., hydrophobic fumedsilica); and wherein the (co)polymerizing conditions comprise a reactiontemperature from 80 degrees (°) to 110° Celsius (C.), alternatively 83°to 106° C., alternatively 83° to 87° C., alternatively 91° to 100° C.,alternatively 101° to 106° C.; a molar ratio of the molecular hydrogengas to the ethylene (H2/C2 molar ratio) from 0.001 to 0.050,alternatively 0.001 to 0.030, alternatively 0.002 to 0.025,alternatively 0.010 to 0.020; and a molar ratio of the comonomer (Comer)to the ethylene (Comer/C2 molar ratio) from 0.005 to 0.10, alternatively0.008 to 0.050, alternatively 0.010 to 0.040. The bimodal LLDPEcomposition may be that of any one of aspects 1 to 6. In an alternativeembodiment of aspect 6 or 7, the bimodal catalyst system may beprepared, and then fed into the polymerization reactor(s) as asuspension (e.g., slurry) in a mineral oil and the trim solution may beprepared, and then fed into the polymerization reactor(s) as a solution,e.g., in a liquid alkane.

Aspect 8. The bimodal linear low density polyethylene composition ofaspect 6 or the method of aspect 7 may be further described by any oneof limitations (i) to (vi): (i) wherein the bimodal catalyst systemconsists essentially of a bis(2-pentamethylphenylamido)ethyl)aminezirconium complex and a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complexin a molar ratio thereof from 1.0:1.0 to 5.0:1.0, respectively,alternatively 1.5:1.0 to 2.5:1.0, alternatively 2.0:1.0 to 4.0:1.0,alternatively 2.5:1.0 to 3.49:1.0, alternatively from 2.7:1.0 to3.3:1.0, alternatively from 2.9:1.0 to 3.1:1.0, alternatively 3.0:1.0,and a methylaluminoxane species, all disposed by spray-drying onto thesolid support; (ii) wherein the bimodal catalyst system further consistsessentially of mineral oil and the solid support is a hydrophobic fumedsilica (e.g., a fumed silica treated with dimethyldichlorosilane); (iii)wherein the mixture is a suspension of the bimodal catalyst system inmineral oil and the trim solution and wherein the mixture is premade andthen fed into the polymerization reactor(s); (iv) wherein the trimsolution is made by dissolving(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl in the inert liquid solvent (e.g., a liquid alkane) to give thetrim solution; (v) wherein the polymerization reactor(s) is onefluidized bed gas phase reactor and the method is a gas phasepolymerization; and (vi) each of (i) to (v). The molar ratio of thebis(2-pentamethylphenylamido)ethyl)amine zirconium complex to the(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complexmay be based on molar ratio of their respective Zr atom contents, whichmay be calculated from ingredient weights (e.g., weights ofbis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl and(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride) or measured analytically.

Aspect 9. A manufactured article comprising a shaped form of the bimodallinear low density polyethylene composition of any one of aspects 1 to6.

Aspect 10. The manufactured article of aspect 9 selected from: films,sheets, and injection molded articles. The manufactured article may be afilm, alternatively a blown film.

Aspect 11. The manufactured article of aspect 9 or 10 selected fromagricultural film, food packaging, garment bags, grocery bags,heavy-duty sacks, industrial sheeting, pallet and shrink wraps, bags,buckets, freezer containers, lids, and toys.

Aspect 12. A method of covering a substance or article in need ofcovering, the method comprising covering or sealing, alternativelysealing at least a portion, alternatively all of the substance or themanufactured article of any one of aspects 9 to 11.

Activator (for activating procatalysts to form catalysts). Also known asco-catalyst. Any metal containing compound, material or combination ofcompounds and/or substances, whether unsupported or supported on asupport material, that can activate a procatalyst to give a catalyst andan activator species. The activating may comprise, for example,abstracting at least one leaving group (e.g., at least one X in any oneof the structural formulas in FIG. 1) from a metal of a procatalyst(e.g., M in any one of the structural formulas in FIG. 1) to give thecatalyst. The catalyst may be generically named by replacing the leavinggroup portion of the name of the procatalyst with “complex”. Forexample, a catalyst made by activatingbis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl may becalled a “bis(2-pentamethylphenylamido)ethyl)amine zirconium complex”. Acatalyst made by activating(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride or(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl may be called a“(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumcomplex”. The catalyst made by activating(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride may be the same as or different than the catalyst made byactivating(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl. The metal of the activator typically is different than themetal of the procatalyst. The molar ratio of metal content of theactivator to metal content of the procatalyst(s) may be from 1000:1 to0.5:1, alternatively 300:1 to 1:1, alternatively 150:1 to 1:1. Theactivator may be a Lewis acid, a non-coordinating ionic activator, or anionizing activator, or a Lewis base, an alkylaluminum, or analkylaluminoxane. The alkylaluminum may be a trialkylaluminum,alkylaluminum halide, or alkylaluminum alkoxide (diethylaluminumethoxide). The trialkylaluminum may be trimethylaluminum,triethylaluminum (“TEAI”), tripropylaluminum, triisobutylaluminum, andthe like. The alkylaluminum halide may be diethylaluminum chloride. Thealkylaluminoxane may be a methyl aluminoxane (MAO), ethyl aluminoxane,or isobutylaluminoxane. The activator may be a MAO that is a modifiedmethylaluminoxane (MMAO). The corresponding activator species may be aderivative of the Lewis acid, non-coordinating ionic activator, ionizingactivator, Lewis base, alkylaluminum, or alkylaluminoxane, respectively.The activator species may have a different structure or composition thanthe activator from which it is derived and may be a by-product of theactivation of the procatalyst or a derivative of the byproduct. Anexample of the derivative of the byproduct is a methylaluminoxanespecies that is formed by devolatilizing during spray-drying of abimodal catalyst system made with methylaluminoxane. The activator maybe commercially available. An activator may be fed into thepolymerization reactor(s) (e.g., one fluidized bed gas phase reactor) ina separate feed from that feeding the reactants used to make the bimodalcatalyst system (e.g., supported bimodal catalyst system) and/or thetrim solution thereinto. The activator may be fed into thepolymerization reactor(s) in “wet mode” in the form of a solutionthereof in an inert liquid such as mineral oil or toluene, in slurrymode as a suspension, or in dry mode as a powder.

Bimodal. Multimodal; having at least 2 peaks, (e.g., 2 or 3 peaks),alternatively only 2 peaks, in a molecular weight distribution (MWD)such as MWD measured by gel permeation chromatography (GPC).

Bimodal catalyst system. A combination of two or more catalyst compoundsindependently useful for enhancing rate of polymerization of a sameolefin monomer and/or comonomer and yields a bimodal polyethylenecomposition. In some aspects the bimodal catalyst system has only twocatalysts, and is prepared from two and only two procatalyst compounds.One of the catalyst compounds may be a metallocene catalyst compound andthe other a non-metallocene catalyst compound. One of the catalystcompounds yields, under the (co)polymerizing conditions, the lowermolecular weight (LMW) polyethylene component and the other catalystcompound yields the higher molecular weight (HMW) polyethylenecomponent. The LMW and HMW polyethylene components together constitutethe bimodal polyethylene composition, which may be the inventive LLDPEcomposition, made with the bimodal catalyst system, and having amultimodal (e.g., bimodal) molecular weight distribution. Typically thebimodal catalyst system, method employing same, and inventive bimodalLLDPE composition is free of a Ziegler-Natta catalyst.

The bimodal catalyst system may be made by contacting at least twoprocatalysts having different structures from each other with at leastone of the activators. Each procatalyst may independently comprise ametal atom, at least one ligand bonded to the metal atom, and at leastone leaving group bonded to and displaceable from the metal atom. Eachmetal may be an element of any one of Groups 3 to 14, e.g., a Group 4metal. Each leaving group is H, an unsubstituted alkyl, an aryl group,an aralkyl group, a halide atom, an alkoxy group, or a primary orsecondary amino group. In metallocenes, at least one ligand is acyclopentadienyl or substituted cyclopentadienyl group. Innon-metallocenes, no ligand is a cyclopentadienyl or substitutedcyclopentadienyl group, and instead at least one ligand has at least oneO, N, and/or P atom that coordinates to the metal atom. Typically theligand(s) of the non-metallocene has at least two O, N, and/or P atomsthat coordinates in a multidentate (e.g., bidentate or tridentate)binding mode to the metal atom. Discrete structures means theprocatalysts and catalysts made therefrom have different ligands fromeach other, and either the same or a different metal atom, and eitherthe same or different leaving groups.

One of the procatalysts, useful for making a catalyst of the bimodalcatalyst system and/or making the trim solution, may be a metallocenecompound of any one of formulas (I) to (IX) and another of theprocatalysts may be a non-metallocene of any one of formulas (A) and(B), wherein the formulas are drawn in FIG. 1.

In formula (I), FIG. 1, each of the R¹ to R¹⁰ groups is independently H,a (C₁-C₂₀)alkyl, (C₆-C₂₀)aryl, or (C₇-C₂₀)aralkyl group; M is a Group 4metal; and each X is independently H, a halide, (C₁-C₂₀)alkyl, or(C₇-C₂₀)aralkyl group. In some aspects each of R⁷ to R¹⁰ is H in formula(I).

In formula (II), FIG. 1, each of the R¹ to R⁶ groups is independently H,a (C₁-C₂₀)alkyl, (C₆-C₂₀)aryl, or (C₇-C₂₀)aralkyl group; M is a Group 4metal (e.g., Ti, Zr, or Hf); and each X is independently H, a halide,(C₁-C₂₀)alkyl, or (C₇-C₂₀)aralkyl group.

In formula (III), FIG. 1, each of the R¹ to R¹² groups is independentlyH, a (C₁-C₂₀)alkyl, (C₆-C₂₀)aryl, or (C₇-C₂₀)aralkyl group, wherein atleast one of R⁴ to R⁷ is not H; M is a Group 4 metal (e.g., Ti, Zr, orHf); and each X is independently H, a halide, (C₁-C₂₀)alkyl, or(C₇-C₂₀)aralkyl group. In some aspects each of R⁹ to R¹² is H in formula(III).

In some aspects each X in formulas (I) to (III) is independently ahalide, (C₁-C₄)alkyl, or benzyl; alternatively Cl or benzyl. In someaspects each halide in formulas (I) to (III) is independently Cl, Br, orI; alternatively Cl or Br; alternatively Cl. In some aspects each M informulas (I) to (III) is independently Ti, Zr, or Hf; alternatively Zror Hf; alternatively Ti; alternatively Zr; alternatively Hf.

In formulas (IV) to (IX), FIG. 1, Me is methyl (CH₃), Pr is propyl(i.e., CH₂CH₂CH₃), and each “I” substituent on a ring represents amethyl group.

In formulas (A) and (B), FIG. 1, M is a Group 3 to 12 transition metalatom or a Group 13 or 14 main group metal atom, or a Group 4, 5, or 6metal atom. M may be a Group 4 metal atom, alternatively Ti, Zr, or Hf;alternatively Zr or Hf; alternatively Zr. Each X is independently aleaving group as described above, such as an anionic leaving group.Subscript y is 0 or 1; when y is 0 group L′ is absent. Subscript nrepresents the formal oxidation state of metal atom M and is +3, +4, or+5; alternatively n is +4. L is a Group 15 or 16 element, such asnitrogen or oxygen; L′ is a Group 15 or 16 element or Group 14containing group, such as carbon, silicon or germanium. Y is a Group 15element, such as nitrogen or phosphorus; alternatively nitrogen. Z is aGroup 15 element, such as nitrogen or phosphorus; alternativelynitrogen. Subscript m is 0, −1, −2 or −3; alternatively −2; andrepresents the total formal charge of the Y, Z, and L in formula (A) andthe total formal charge of the Y, Z, and L′ in formula (B). R¹, R², R³,R⁴, R⁵, R⁶, and R⁷ are independently H, a (C₁-C₂₀)hydrocarbyl group, a(C₁-C₂₀)heterohydrocarbyl group, or a (C₁-C₂₀)organoheteryl group,wherein the (C₁-C₂₀)heterohydrocarbyl group and (C₁-C₂₀)organoheterylgroup each independently have at least one heteroatom selected from Si,Ge, Sn, Pb, or P. Alternatively, R¹ and R² are covalently bonded to eachother to form a divalent group of formula —R^(1a)—R^(2a)— and/or R⁴ andR⁵ are covalently bonded to each other to form a divalent group offormula —R^(4a)—R^(5a)—, wherein —R^(1a)—R^(2a)— and —R^(4a)—R^(5a)— areindependently a (C₁-C₂₀)hydrocarbylene group, a(C₁-C₂₀)heterohydrocarbylene group, or a (C₁-C₂₀)organoheterylene group.R³ may be absent; alternatively R³ is H, a halogen atom, a(C₁-C₂₀)hydrocarbyl group, a (C₁-C₂₀)heterohydrocarbyl group, or a(C₁-C₂₀)organoheteryl group. R³ is absent if, for example, L is O, H, oran alkyl group. R⁴ and R⁵ may be a (C₁-C₂₀)alkyl group, a (C₆-C₂₀)arylgroup, a substituted (C₆-C₂₀)aryl group, a (C₃-C₂₀)cycloalkyl group, asubstituted (C₃-C₂₀)cycloalkyl group, a (C₈-C₂₀)bicyclic aralkyl group,or a substituted (C₈-C₂₀)bicyclic aralkyl group. R⁶ and R⁷ may be H orabsent. R* may be absent, or may be a hydrogen, a Group 14 atomcontaining group, a halogen, or a heteroatom containing group.

In some aspects the bimodal catalyst system may comprise a combinationof a metallocene catalyst compound and a non-metallocene catalystcompound. The metallocene catalyst compound may be a metalloceneligand-metal complex such as a metallocene ligand-Group 4 metal complex,which may be made by activating (with the activator) a procatalystcompound selected from(pentamethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride, bis(n-butylcyclopentadienyl)zirconium dichloride,(pentamethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl, and bis(n-butylcyclopentadienyl)zirconium dimethyl. Thenon-metallocene catalyst compound may be a non-metallocene ligand-metalcomplex such as a non-metallocene ligand-Group 4 metal complex, whichmay be made by activating (with the activator) a procatalyst compoundselected from bis(2-(2,4,6-trimethylphenylamido)ethyl)amine zirconiumdibenzyl and bis(2-(pentamethylphenylamido)ethyl)amine zirconiumdibenzyl.

In some aspects the bimodal catalyst system may be made by activating,according to the method of contacting with an activator, a combinationof a metallocene procatalyst compound that is(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride and a non-metallocene procatalyst compound that isbis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl. The(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride is a compound of formula (II) wherein M is Zr, each X is Cl,R⁶ is propyl (CH₂CH₂CH₃), and each of R¹ to R⁴ is methyl. Thebis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl is aprocatalyst compound of formula (A) wherein M is Zr, each X is benzyl,R¹ and R² are each CH₂CH₂; R³ is H; L, Y, and Z are all N; and R⁴ and R⁵are each pentamethylphenyl; and R⁶ and R⁷ are absent.

Each of the catalyst compounds of the bimodal catalyst systemindependently may be unsupported, alternatively supported on a supportmaterial, in which latter case the bimodal catalyst system is asupported catalyst system. When each catalyst compound is supported, thecatalyst compounds may reside on the same support material (e.g., sameparticles), or on different support materials (e.g., differentparticles). The bimodal catalyst system includes mixtures of unsupportedcatalyst compounds in slurry form and/or solution form. The supportmaterial may be a silica (e.g., fumed silica), alumina, a clay, or talc.The fumed silica may be hydrophilic (untreated), alternativelyhydrophobic (treated). In some aspects the support is the hydrophobicfumed silica, which may be prepared by treating an untreated fumedsilica with a treating agent such as dimethyldichlorosilane, apolydimethylsiloxane fluid, or hexamethyldisilazane. In some aspects thetreating agent is dimethyldichlorosilane.

In some aspects the bimodal catalyst system is the bimodal catalystsystem described in any one of the following references: U.S. Pat. Nos.7,193,017 B2; 7,312,279 B2; 7,858,702 B2; 7,868,092 B2; 8,202,940 B2;and 8,378,029 B2 (e.g., column 4/line 60 to column 5/line 10 and column10/lines 6 to 38 and Example 1).

The bimodal catalyst system may be fed into the polymerizationreactor(s) in “dry mode” or “wet mode”, alternatively dry mode,alternatively wet mode. The dry mode is fed in the form of a dry powderor granules. The wet mode is fed in the form of a suspension of thebimodal catalyst system in an inert liquid such as mineral oil. Thebimodal catalyst system is commercially available under the PRODIGY™Bimodal Catalysts brand, e.g., BMC-200, from Univation Technologies,LLC. (C₃-C₂₀)alpha-olefin. A compound of formula (I): H₂C═C(H)—R (I),wherein R is a straight chain (C₁-C₁₈)alkyl group. (C₁-C₁₈)alkyl groupis a monovalent unsubstituted saturated hydrocarbon having from 1 to 18carbon atoms. Examples of R are methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. In someembodiments the (C₃-C₂₀)alpha-olefin is 1-propene, 1-butene, 1-hexene,or 1-octene; alternatively 1-butene, 1-hexene, or 1-octene;alternatively 1-butene or 1-hexene; alternatively 1-butene or 1-octene;alternatively 1-hexene or 1-octene; alternatively 1-butene;alternatively 1-hexene; alternatively 1-octene; alternatively acombination of any two of 1-butene, 1-hexene, and 1-octene. The(C₃-C₂₀)alpha-olefin is used as a comonomer from which the comonomericunits of the LMW polyethylene component are derived may be the same as,alternatively different than, the (C₃-C₂₀)alpha-olefin from which thecomonomeric units of the HMW polyethylene component are derived.

Consisting essentially of, consist(s) essentially of, and the like.Partially-closed ended expressions that exclude anything that wouldaffect the basic and novel characteristics of that which they describe,but otherwise allow anything else. As applied to the description of abimodal catalyst system embodiment consisting essentially ofbis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl and(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride, both disposed on a solid support and activated with anactivating agent, the expression means the embodiment does not contain aZiegler-Natta catalyst or any organic ligand other than thebis(2-pentamethylphenylamido)ethyl)amine, benzyl,tetramethylcyclopentadienyl, and n-propylcyclopentadienyl ligands. Oneor more of the benzyl and chloride leaving groups may be absent from theZr in the bimodal catalyst system. The expression “consistingessentially of” as applied to the description of the “trim solutionmeans the trim solution is unsupported (i.e., not disposed on aparticulate solid) and is free of a Ziegler-Natta catalyst or anyorganic ligand other than the tetramethylcyclopentadienyl andn-propylcyclopentadienyl ligands. The expression “consist essentiallyof” as applied to a dry inert purge gas means that the dry inert purgegas is free of, alternatively has less than 5 parts per million based ontotal parts by weight of gas of water or any reactive compound thatcould oxidize a constituent of the present polymerization reaction. Insome aspects any one, alternatively each “comprising” or “comprises” maybe replaced by “consisting essentially of” or “consists essentially of”,respectively; alternatively by “consisting of” or “consists of”,respectively.

Consisting of and consists of. Closed ended expressions that excludeanything that is not specifically described by the limitation that itmodifies. In some aspects any one, alternatively each expression“consisting essentially of” or “consists essentially of” may be replacedby the expression “consisting of” or “consists of”, respectively.

(Co)polymerizing conditions. Any result effective variable orcombination of such variables, such as catalyst composition; amount ofreactant; molar ratio of two reactants; absence of interfering materials(e.g., H₂O and O₂); or a process parameter (e.g., feed rate ortemperature), step, or sequence that is effective and useful for theinventive copolymerizing method in the polymerization reactor(s) to givethe inventive bimodal LLDPE composition.

At least one, alternatively each of the (co)polymerizing conditions maybe fixed (i.e., unchanged) during production of the inventive bimodalLLDPE composition. Such fixed (co)polymerizing conditions may bereferred to herein as steady-state (co)polymerizing conditions.Steady-state (co)polymerizing conditions are useful for continuouslymaking embodiments of the inventive bimodal LLDPE composition havingsame polymer properties.

Alternatively, at least one, alternatively two or more of the(co)polymerizing conditions may be varied within their defined operatingparameters during production of the inventive bimodal LLDPE compositionin order to transition from the production of a first embodiment of theinventive bimodal LLDPE composition having a first set of polymerproperties to a second embodiment of the inventive bimodal LLDPEcomposition having a second set of polymer properties, wherein the firstand second sets of polymer properties are different and are each withinthe limitations described herein for the inventive bimodal LLDPEcomposition. For example, all other (co)polymerizing conditions beingequal, a higher molar ratio of (C₃-C₂₀)alpha-olefin comonomer/ethylenefeeds in the inventive method of copolymerizing produces a lower densityof the resulting product inventive bimodal LLDPE composition. At a givenmolar ratio of comonomer/ethylene, the molar ratio of the procatalyst ofthe trim solution relative to total moles of catalyst compounds of thebimodal catalyst system may be varied to adjust the density, melt index,melt flow, molecular weight, and/or melt flow ratio thereof. Toillustrate an approach to making transitions, perform one of the laterdescribed inventive copolymerization examples to reach steady-state(co)polymerizing conditions. Then change one of the (co)polymerizingconditions to begin producing a new embodiment of the inventive bimodalLLDPE composition. Sample the new embodiment, and measure a propertythereof. If necessary, repeat the change condition/sampleproduct/measure property steps at intervals until the measurement showsthe desired value for the property is obtained. An example of suchvarying of an operating parameter includes varying the operatingtemperature within the aforementioned range from 83° to 87° C. such asby changing from a first operating temperature of 85° C. to a secondoperating temperature of 86° C., or by changing from a third operatingtemperature of 87° C. to a third operating temperature of 85° C.Similarly, another example of varying an operating parameter includesvarying the molar ratio of molecular hydrogen to ethylene (H2/C2) from0.017 to 0.018, or from 0.020 to 0.019. Similarly, another example ofvarying an operating parameter includes varying the molar ratio ofcomonomer (Comer) to the ethylene (Comer/C2 molar ratio) from 0.028 to0.038, or from 0.041 to 0.025. Combinations of two or more of theforegoing example variations are included herein. Transitioning from oneset to another set of the (co)polymerizing conditions is permittedwithin the meaning of “(co)polymerizing conditions” as the operatingparameters of both sets of (co)polymerizing conditions are within theranges defined therefore herein. A beneficial consequence of theforegoing transitioning is that any described property value for theinventive bimodal LLDPE composition, or the LMW or HMW polyethylenecomponent thereof, may be achieved by a person of ordinary skill in theart in view of the teachings herein.

The (co)polymerizing conditions may further include a high pressure,liquid phase or gas phase polymerization reactor and polymerizationmethod to yield the inventive bimodal LLDPE composition. Such reactorsand methods are generally well-known in the art. For example, the liquidphase polymerization reactor/method may be solution phase or slurryphase such as described in U.S. Pat. No. 3,324,095. The gas phasepolymerization reactor/method may employ the inert condensing agent andbe conducted in condensing mode polymerization such as described in U.S.Pat. Nos. 4,453,399; 4,588,790; 4,994,534; 5,352,749; 5,462,999; and6,489,408. The gas phase polymerization reactor/method may be afluidized bed reactor/method as described in U.S. Pat. Nos. 3,709,853;4,003,712; 4,011,382; 4,302,566; 4,543,399; 4,882,400; 5,352,749;5,541,270; EP-A-0 802 202; and Belgian Patent No. 839,380. These patentsdisclose gas phase polymerization processes wherein the polymerizationmedium is either mechanically agitated or fluidized by the continuousflow of the gaseous monomer and diluent. Other gas phase processescontemplated include series or multistage polymerization processes suchas described in U.S. Pat. Nos. 5,627,242; 5,665,818; 5,677,375; EP-A-0794 200; EP-B1-0 649 992; EP-A-0 802 202; and EP-B-634421.

The (co)polymerizing conditions for gas or liquid phase reactors/methodsmay further include one or more additives such as a chain transferagent, a promoter, or a scavenging agent. The chain transfer agents arewell known and may be alkyl metal such as diethyl zinc. Promoters arewell known such as in U.S. Pat. No. 4,988,783 and may includechloroform, CFCl3, trichloroethane, and difluorotetrachloroethane.Scavenging agents may be a trialkylaluminum. Slurry or gas phasepolymerizations may be operated free of (not deliberately added)scavenging agents. The (co)polymerizing conditions for gas phasereactors/polymerizations may further include an amount (e.g., 0.5 to 200ppm based on all feeds into reactor) static control agents and/orcontinuity additives such as aluminum stearate or polyethyleneimine.Static control agents may be added to the gas phase reactor to inhibitformation or buildup of static charge therein.

The (co)polymerizing conditions may further include using molecularhydrogen to control final properties of the LMW and/or HMW polyethylenecomponents or inventive bimodal LLDPE composition. Such use of H₂ isgenerally described in Polypropylene Handbook 76-78 (Hanser Publishers,1996). All other things being equal, using hydrogen can increase themelt flow rate (MFR) or melt index (MI) thereof, wherein MFR or MI areinfluenced by the concentration of hydrogen. A molar ratio of hydrogento total monomer (H₂/monomer), hydrogen to ethylene (H₂/C₂), or hydrogento comonomer (H₂/α-olefin) may be from 0.0001 to 10, alternatively0.0005 to 5, alternatively 0.001 to 3, alternatively 0.001 to 0.10.

The (co)polymerizing conditions may include a partial pressure ofethylene in the polymerization reactor(s) independently from 690 to 3450kilopascals (kPa, 100 to 500 pounds per square inch absolute (psia),alternatively 1030 to 2070 kPa (150 to 300 psia), alternatively 1380 to1720 kPa (200 to 250 psia), alternatively 1450 to 1590 kPa (210 to 230psia), e.g., 1520 kPa (220 psia). 1.000 psia=6.8948 kPa.

Dry. Generally, a moisture content from 0 to less than 5 parts permillion based on total parts by weight. Materials fed to thepolymerization reactor(s) during a polymerization reaction under(co)polymerizing conditions typically are dry.

Ethylene. A compound of formula H₂C═CH₂. A polymerizable monomer.

Feeds. Quantities of reactants and/or reagents that are added or “fed”into a reactor. In continuous polymerization operation, each feedindependently may be continuous or intermittent. The quantities or“feeds” may be measured, e.g., by metering, to control amounts andrelative amounts of the various reactants and reagents in the reactor atany given time.

Film: for claiming purposes, measure properties on 25 micrometers thickmonolayer films.

Higher molecular weight (HMW). Relative to LMW, having a higher weightaverage molecular weight (M_(w)). The HMW polyethylene component of theinventive bimodal LLDPE composition may have an M_(w) from 10,000 to1,000,000 g/mol. The lower endpoint of the M_(w) for the HMWpolyethylene component may be 20,000, alternatively 50,000,alternatively 100,000, alternatively 150,000, alternatively 200,000,alternatively 250,000, alternatively 300,000 g/mol. The upper endpointof M_(w) may be 900,000, alternatively 800,000, alternatively 700,000,alternatively 600,000 g/mol. In describing the inventive bimodal LLDPEcomposition, the bottom portion of the range of M_(w) for the HMWpolyethylene component may overlap the upper portion of the range ofM_(w) for the LMW polyethylene component, with the proviso that in anyembodiment of the inventive bimodal LLDPE composition the particularM_(w) for the HMW polyethylene component is greater than the particularM_(w) for the LMW polyethylene component. The HMW polyethylene componentmay be made with catalyst prepared by activating a non-metalloceneligand-Group 4 metal complex.

Inert. Generally, not (appreciably) reactive or not (appreciably)interfering therewith in the inventive polymerization reaction. The term“inert” as applied to the purge gas or ethylene feed means a molecularoxygen (O₂) content from 0 to less than 5 parts per million based ontotal parts by weight of the purge gas or ethylene feed.

Inert condensing agent (ICA). An inert liquid useful for coolingmaterials in the polymerization reactor(s) (e.g., a fluidized bedreactor). In some aspects the ICA is a (C₅-C₂₀)alkane, alternatively a(C₁₁-C₂₀)alkane, alternatively a (C₅-C₁₀)alkane. In some aspects the ICAis a (C₅-C₁₀)alkane. In some aspects the (C₅-C₁₀)alkane is a pentane,e.g., normal-pentane or isopentane; a hexane; a heptane; an octane; anonane; a decane; or a combination of any two or more thereof. In someaspects the ICA is isopentane (i.e., 2-methylbutane). The inventivemethod of polymerization, which uses the ICA, may be referred to hereinas being an inert condensing mode operation (ICMO). Concentration in gasphase measured using gas chromatography by calibrating peak area percentto mole percent (mol %) with a gas mixture standard of knownconcentrations of ad rem gas phase components. Concentration may be from1 to 10 mol %, alternatively from 3 to 8 mole %.

Lower molecular weight (LMW). Relative to HMW, having a lower weightaverage molecular weight (M_(w)). The LMW polyethylene component of theinventive bimodal LLDPE composition may have an M_(w) from 3,000 to100,000 g/mol. The lower endpoint of the M_(w) for the LMW polyethylenecomponent may be 5,000, alternatively 8,000, alternatively 10,000,alternatively 12,000, alternatively 15,000, alternatively 20,000 g/mol.The upper endpoint of M_(w) may be 50,000, alternatively 40,000,alternatively 35,000, alternatively 30,000 g/mol. The LMW polyethylenecomponent may be made with catalyst prepared by activating a metalloceneligand-Group 4 metal complex.

Polyethylene. A macromolecule, or collection of macromolecules, composedof repeat units wherein 50 to 100 mole percent (mol %), alternatively 70to 100 mol %, alternatively 80 to 100 mol %, alternatively 90 to 100 mol%, alternatively 95 to 100 mol %, alternatively any one of the foregoingranges wherein the upper endpoint is <100 mol %, of such repeat unitsare derived from ethylene monomer, and, in aspects wherein there areless than 100 mol % ethylenic repeat units, the remaining repeat unitsare comonomeric units derived from at least one (C₃-C₂₀)alpha-olefin; orcollection of such macromolecules. Linear low density polyethylene(LLDPE). The macromolecule having a substantially linear structure.

Procatalyst. Also referred to as a precatalyst or catalyst compound (asopposed to active catalyst compound), generally a material, compound, orcombination of compounds that exhibits no or extremely lowpolymerization activity (e.g., catalyst efficiency may be from 0 or<1,000) in the absence of an activator, but upon activation with anactivator yields a catalyst that shows at least 10 times greatercatalyst efficiency than that, if any, of the procatalyst.

Resolved (GPC chromatogram). A molecular weight distribution having twopeaks separated by an intervening local minimum. For example, a resolvedGPC chromatogram of the inventive polymers represented by a plot ofdW/dlog(MW) versus log(MW) that features local maxima dW/dlog(MW) valuesfor the LMW and HMW polyethylene component peaks, and a local minimumdW/dlog(MW) value at a log(MW) between the maxima. The at least someseparation of the peaks for the LMW and HMW polyethylene components inthe chromatogram of the GPC. Typically the separation may not be down tobaseline.

Start-up or restart of the polymerization reactor(s) illustrated with afluidized bed reactor. The start-up of a recommissioned fluidized bedreactor (cold start) or restart of a transitioning fluidized bed reactor(warm start/transition) includes a time period that is prior to reachingthe (co)polymerizing conditions. Start-up or restart may include the useof a seedbed preloaded or loaded, respectively, into the fluidized bedreactor. The seedbed may be composed of powder of polyethylene. Thepolyethylene of the seedbed may be a LDPE, alternatively a LLDPE,alternatively a bimodal LLDPE, alternatively a previously madeembodiment of the inventive bimodal LLDPE composition.

Start-up or restart of the fluidized bed reactor may also include gasatmosphere transitions comprising purging air or other unwanted gas(es)from the reactor with a dry (anhydrous) inert purge gas, followed bypurging the dry inert purge gas from the reactor with dry ethylene gas.The dry inert purge gas may consist essentially of molecular nitrogen(N₂), argon, helium, or a mixture of any two or more thereof. When notin operation, prior to start-up (cold start), the fluidized bed reactorcontains an atmosphere of air. The dry inert purge gas may be used tosweep the air from a recommissioned fluidized bed reactor during earlystages of start-up to give a fluidized bed reactor having an atmosphereconsisting of the dry inert purge gas. Prior to restart (e.g., after achange in seedbeds or prior to a change in alpha-olefin comonomer), atransitioning fluidized bed reactor may contain an atmosphere ofunwanted alpha-olefin, unwanted ICA or other unwanted gas or vapor. Thedry inert purge gas may be used to sweep the unwanted vapor or gas fromthe transitioning fluidized bed reactor during early stages of restartto give the fluidized bed reactor having an atmosphere consisting of thedry inert purge gas. Any dry inert purge gas may itself be swept fromthe fluidized bed reactor with the dry ethylene gas. The dry ethylenegas may further contain molecular hydrogen gas such that the dryethylene gas is fed into the fluidized bed reactor as a mixture thereof.Alternatively the dry molecular hydrogen gas may be introducedseparately and after the atmosphere of the fluidized bed reactor hasbeen transitioned to ethylene. The gas atmosphere transitions may bedone prior to, during, or after heating the fluidized bed reactor to thereaction temperature of the (co)polymerizing conditions.

Start-up or restart of the fluidized bed reactor also includesintroducing feeds of reactants and reagents thereinto. The reactantsinclude the ethylene and the alpha-olefin. The reagents fed into thefluidized bed reactor include the molecular hydrogen gas and the inertcondensing agent (ICA) and the mixture of the bimodal catalyst systemand the trim solution.

Substance or article in need of covering. A naturally occurring orman-made material, or manufactured article that would benefit fromhaving a layer of the inventive bimodal LLDPE composition thereover,therearound, or thereon. Substances in need of covering include thosevulnerable to their external environments and those in need ofsegregation therefrom. External environments may contain oxygen,moisture, and/or light, which may degrade such substances but for thelayer of the inventive bimodal LLDPE composition. Such substancesinclude clothing, drugs, food, electronic components, hygroscopiccompounds, plants, and any other light, oxygen and/or moisture-sensitivematerial or manufactured article. Articles in need of covering includeordered arrangements of materials (e.g., stacks of manufactured articleson a pallet in need of wrapping), boxes in need of shrink wrapping,loose manufactured articles in need of shipping, and toxic or corrosivematerials.

Trim solution. Any one of the metallocene procatalyst compounds or thenon-metallocene procatalyst compounds described earlier dissolved in theinert liquid solvent (e.g., liquid alkane). The trim solution is mixedwith the bimodal catalyst system to make the mixture, and the mixture isused in the inventive polymerization reaction to modify at least oneproperty of the inventive bimodal LLDPE composition made thereby.Examples of such at least one property are density, melt index MI2, flowindex FI21, melt flow ratio, and molecular mass dispersity(M_(w)/M_(n)), Ð_(M). The mixture of the bimodal catalyst system and thetrim solution may be fed into the polymerization reactor(s) in “wetmode”, alternatively may be devolatilized and fed in “dry mode”. The drymode is fed in the form of a dry powder or granules. When mixturecontains a solid support, the wet mode is fed in the form of asuspension or slurry. In some aspects the inert liquid is a liquidalkane such as heptane.

Ziegler-Natta catalysts. Heterogeneous materials that enhance olefinpolymerization reaction rates and typically are products that areprepared by contacting inorganic titanium compounds, such as titaniumhalides supported on a magnesium chloride support, with an activator.The activator may be an alkylaluminum activator such as triethylaluminum(TEA), triisobutylaluminum (TIBA), diethylaluminum chloride (DEAC),diethylaluminum ethoxide (DEAE), or ethylaluminum dichloride (EADC).

Advantageously we discovered the inventive bimodal LLDPE composition. Itunpredictably has at least one improved property such as, for example,at least one improved (increased) processability property and/or atleast one improved (increased) stiffness property. The improvedprocessability property may be at least one of decreased extruder barrelpressure, increased sealability (e.g., hot seal/hot tack), decreased tandelta value, and increased shear thinning index value. The improvedstiffness property may be at least one of increased Elmendorf tear (CDTear), increased melt strength, and increased secant modulus. In someaspects the inventive bimodal LLDPE composition is not characterized bya worsening of any three, alternatively any two, alternatively any oneof the foregoing properties.

Test samples of embodiments of unfilled and filled compositions may beseparately made into compression molded plaques. The mechanicalproperties of these compositions may be characterized using test samplescut from the compression molded plaques.

A compound includes all its isotopes and natural abundance andisotopically-enriched forms. The enriched forms may have medical oranti-counterfeiting uses.

In some aspects any compound, composition, formulation, mixture, orreaction product herein may be free of any one of the chemical elementsselected from the group consisting of: H, Li, Be, B, C, N, O, F, Na, Mg,Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge,As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb,Te, I, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, TI, Pb, Bi,lanthanoids, and actinoids; with the proviso that chemical elementsrequired by the compound, composition, formulation, mixture, or reactionproduct (e.g., C and H required by a polyolefin or C, H, and O requiredby an alcohol) are not excluded.

The following apply unless indicated otherwise. Alternatively precedes adistinct embodiment. ASTM means the standards organization, ASTMInternational, West Conshohocken, Pa., USA. ISO means the standardsorganization, International Organization for Standardization, Geneva,Switzerland. Any comparative example is used for illustration purposesonly and shall not be prior art. Free of or lacks means a completeabsence of; alternatively not detectable. IUPAC is International Unionof Pure and Applied Chemistry (IUPAC Secretariat, Research TrianglePark, N.C., USA). May confers a permitted choice, not an imperative.Operative means functionally capable or effective. Optional(ly) means isabsent (or excluded), alternatively is present (or included). Propertiesare measured using a standard test method and conditions for themeasuring (e.g., viscosity: 23° C. and 101.3 kPa). Ranges includeendpoints, subranges, and whole and/or fractional values subsumedtherein, except a range of integers does not include fractional values.Room temperature: 23° C.±1° C. Substituted when referring to a compoundmeans having, in place of hydrogen, one or more substituents, up to andincluding per substitution.

Bimodality Test Method: determine presence or absence of resolvedbimodality by plotting dWf/dLogM (mass detector response) on y-axisversus LogM on the x-axis to obtain a GPC chromatogram curve containinglocal maxima log(MW) values for LMW and HMW polyethylene componentpeaks, and observing the presence or absence of a local minimum betweenthe LMW and HMW polyethylene component peaks. The dWf is change inweight fraction, dLogM is also referred to as dLog(MW) and is change inlogarithm of molecular weight, and LogM is also referred to as Log(MW)and is logarithm of molecular weight.

Dart Impact Test Method: measured according to ASTM D1709-16a, StandardTest Methods for Impact Resistance of Plastic Film by the Free-FallingDart Test Method, Method A. Method A employs a dart with a 38.10±0.13-mm(1,500±0.005-in.) diameter hemispherical head dropped from a height of0.66±0.01 m (26.0±0.4 in.). This test method can be used for films whoseimpact resistances require masses of about 50 g or less to about 6 kg tofracture them. Results expressed in grams (g).

Deconvoluting Test Method: segment the chromatogram obtained using theBimodality Test Method into nine (9) Schulz-Flory molecular weightdistributions. Such deconvolution method is described in U.S. Pat. No.6,534,604. Assign the lowest four MW distributions to the LMWpolyethylene component and the five highest MW distributions to the HMWpolyethylene component. Determine the respective weight percents (wt %)for each of the LMW and HMW polyethylene components in the inventivebimodal LLDPE composition by using summed values of the weight fractions(Wf) of the LMW and HMW polyethylene components and the respectivenumber average molecular weights (M_(n)) and weight average molecularweights (M_(w)) by known mathematical treatment of aggregatedSchulz-Flory MW distributions.

Density Test Method: measured according to ASTM D792-13, Standard TestMethods for Density and Specific Gravity (Relative Density) of Plasticsby Displacement, Method B (for testing solid plastics in liquids otherthan water, e.g., in liquid 2-propanol). Report results in units ofgrams per cubic centimeter (g/cm³).

Elmendorf Tear Test Method: measured according to ASTM D1922-09,Standard Test Methods for Propagation Tear Resistance of Plastic Filmand Thin Sheeting by Pendulum Method, Type B (constant radius).(Technically equivalent to ISO 6383-2.) Report results as normalizedtear in cross direction (CD) or machine direction (MD) in gram-force(gf).

Flow Index (190° C., 21.6 kg, “F1₂₁”) Test Method: use ASTM D1238-13,Standard Test Method for Melt Flow Rates of Thermoplastics by ExtrusionPlatometer, using conditions of 190° C./21.6 kilograms (kg). Reportresults in units of grams eluted per 10 minutes (g/10 min.) or theequivalent in decigrams per 1.0 minute (dg/1 min.).

Flow Rate (190° C., 5.0 kg, “FR₅”) Test Method: use ASTM D1238-13, usingconditions of 190° C./5.0 kg. Report results in units of grams elutedper 10 minutes (g/10 min.) or the equivalent in decigrams per 1.0 minute(dg/1 min.).

Flow Rate Ratio: (190° C., “FI₂₁/FI₅”) Test Method: calculated bydividing the value from the Flow Index FI₂₁ Test Method by the valuefrom the Flow Index FI₅ Test Method.

Gel permeation chromatography (GPC) Method: Weight-Average MolecularWeight Test Method: determine M_(w), number average molecular weight(M_(n)), and M_(w)/M_(n) using chromatograms obtained on a HighTemperature Gel Permeation Chromatography instrument (HTGPC, PolymerLaboratories). The HTGPC is equipped with transfer lines, a differentialrefractive index detector (DRI), and three Polymer Laboratories PLgel 10μm Mixed-B columns, all contained in an oven maintained at 160° C.Method uses a solvent composed of BHT-treated TCB at nominal flow rateof 1.0 milliliter per minute (mL/min.) and a nominal injection volume of300 microliters (μL). Prepare the solvent by dissolving 6 grams ofbutylated hydroxytoluene (BHT, antioxidant) in 4 liters (L) of reagentgrade 1,2,4-trichlorobenzene (TCB), and filtering the resulting solutionthrough a 0.1 micrometer (μm) Teflon filter to give the solvent. Degasthe solvent with an inline degasser before it enters the HTGPCinstrument. Calibrate the columns with a series of monodispersedpolystyrene (PS) standards. Separately, prepare known concentrations oftest polymer dissolved in solvent by heating known amounts thereof inknown volumes of solvent at 160° C. with continuous shaking for 2 hoursto give solutions. (Measure all quantities gravimetrically.) Targetsolution concentrations, c, of test polymer of from 0.5 to 2.0milligrams polymer per milliliter solution (mg/mL), with lowerconcentrations, c, being used for higher molecular weight polymers.Prior to running each sample, purge the DRI detector. Then increase flowrate in the apparatus to 1.0 mL/min/, and allow the DRI detector tostabilize for 8 hours before injecting the first sample. Calculate M_(w)and M_(n) using universal calibration relationships with the columncalibrations. Calculate MW at each elution volume with followingequation:

${{\log\; M_{X}} = {\frac{\log\left( {K_{X}/K_{PS}} \right)}{a_{X} + 1} + {\frac{a_{PS} + 1}{a_{X} + 1}\log\; M_{PS}}}},$where subscript “X” stands for the test sample, subscript “PS” standsfor PS standards, a_(PS)=0.67, K_(PS)=0.000175, and a_(X) and K_(X) areobtained from published literature. For polyethylenes,a_(X)/K_(X)=0.695/0.000579. For polypropylenesa_(X)/K_(X)=0.705/0.0002288. At each point in the resultingchromatogram, calculate concentration, c, from a baseline-subtracted DRIsignal, I_(DRI), using the following equation: c=K_(DRI)I_(DRI)/(dn/dc),wherein K_(DRI) is a constant determined by calibrating the DRI, /indicates division, and dn/dc is the refractive index increment for thepolymer. For polyethylene, dn/dc=0.109. Calculate mass recovery ofpolymer from the ratio of the integrated area of the chromatogram ofconcentration chromatography over elution volume and the injection masswhich is equal to the pre-determined concentration multiplied byinjection loop volume. Report all molecular weights in grams per mole(g/mol) unless otherwise noted. Further details regarding methods ofdetermining Mw, Mn, MWD are described in US 2006/0173123 page 24-25,paragraphs [0334] to [0341]. Plot of dW/dLog(MW) on the y-axis versusLog(MW) on the x-axis to give a GPC chromatogram, wherein Log(MW) anddW/dLog(MW) are as defined above.

Long Chain Branching (LCB) Test Method: calculate number of long chainbranches (LCB) per 1,000 carbon atoms of a test polymer using acorrelation developed by Janzen and Colby (J. Mol. Struct., 485/486,569-584 (1999)) between zero shear viscosity, η_(O), and M_(W). Theircorrelation is drawn as a reference line on a reference graph of η_(O)on the y-axis and M_(W) on the x-axis. Then a test polymer ischaracterized by (a) and (b): (a) using the Zero Shear ViscosityDetermination Method described later, measuring the test polymer'ssmall-strain (10%) oscillatory shear, and using a three parameterCarreau-Yasuda empirical model (“CY Model”) to determine values forη_(O) therefrom; and (b) using the GPC Test Method described earlier,measuring the test polymer's M_(W). Plot the results for the testpolymer's η_(O) and M_(W) on the reference graph, and compare them tothe reference line. Results for test polymers with zero (0) long chainbranching per 1,000 carbon atoms will plot below the Janzen and Colbyreference line, whereas results for test polymers having long chainbranching >0 per 1,000 carbon atoms will plot above the Janzen and Colbyreference line. The CY Model is well-known from R. B. Bird, R. C.Armstrong, & O. Hasseger, Dynamics of Polymeric Liquids, Volume 1, FluidMechanics, 2^(nd) Edition, John Wiley & Sons, 1987; C. A. Hieber & H. H.Chiang, Rheol. Acta, 1989, 28: 321; and C. A. Hieber & H. H. Chiang,Polym. Eng. Sci., 1992, 32: 931.

Melt Flow Ratio (190° C., “MI₂₁/MI₂”) Test Method: calculated bydividing the value from the Flow Index FI₂₁ Test Method by the valuefrom the Melt Index MI₂ Test Method.

Melt Index (190° C., 2.16 kilograms (kg), “MI₂”) Test Method: forethylene-based (co)polymer is measured according to ASTM D1238-13, usingconditions of 190° C./2.16 kg, formerly known as “Condition E” and alsoknown as MI₂. Report results in units of grams eluted per 10 minutes(g/10 min.) or the equivalent in decigrams per 1.0 minute (dg/1 min.).10.0 dg=1.00 g. Melt index is inversely proportional to the weightaverage molecular weight of the polyethylene, although the inverseproportionality is not linear. Thus, the higher the molecular weight,the lower the melt index.

1% or 2% Secant Modulus Test Method: measured according to ASTM D882-12,Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.Used either 1% or 2% secant modulus in cross direction (CD) or machinedirection (MD). Report results in megapascals (MPa). 1,000.0 pounds persquare inch (psi)=6.8948 MPa.

Shear Thinning Index (SHI) Test Method: Perform small-strain (10%)oscillatory shear measurements on polymer melts at 190° C. using anARES-G2 Advanced Rheometric Expansion System, from TA Instruments, withparallel-plate geometry to obtain the values of storage modulus (G′),loss modulus (G″) complex modulus (G*) and complex viscosity (η*) as afunction of frequency (ω). Obtain a SHI value by calculating the complexviscosities at given values of complex modulus, and calculating theratio of the two viscosities. For example, using the values of complexmodulus of 1 kilopascal (kPa) and 100 kPa, obtain the η*(1.0 kPa) andη*(100 kPa) at a constant value of complex modulus of 1.0 kPa and 100kPa, respectively. The shear thinning index SHI(1/100) is defined as theratio of the two viscosities η*(1.0 kPa) and η*(100 kPa), i.e.η*(1.0)/η*(100).

Tan Delta Test Method: a dynamic mechanical analysis (DMA) methodmeasured at 190° C. and 0.1000 radians per second (rad/s) using thefollowing procedure: Perform small-strain (10%) oscillatory shearmeasurements on polymer melts at 190° C. using an ARES-G2 AdvancedRheometric Expansion System, from TA Instruments, with parallel-plategeometry to obtain the values of storage modulus (G′), loss modulus (G″)complex modulus (G*) and complex viscosity (η*) as a function offrequency (ω). A tan delta (δ) at a particular frequency (ω) is definedas the ratio of loss modulus (G″) to storage modulus (G′) obtained atthat frequency (ω), i.e. tan δ=G″/G′. The tan δ value at frequency (ω)0.1 radian/second is used later in Table 2.

Tensile Modulus Test Method: measured according to ASTM D882-12,Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.Report results in cross direction (CD) as average strain at yield inpercent (%) or average stress at yield in megapascals (MPa), or inmachine direction (MD) as average strain at yield in percent (%).1,000.0 pounds per square inch (psi)=6.8948 MPa.

Zero Shear Viscosity Determination Method: perform small-strain (10%)oscillatory shear measurements on polymer melts at 190° C. using anARES-G2 Advanced Rheometric Expansion System, from TA Instruments, withparallel-plate geometry to obtain complex viscosity η* versus frequency(ω) data. Determine values for the three parameters—zero shearviscosity, η_(O), characteristic viscous relaxation time, τ_(η), and thebreadth parameter, a, —by curve fitting the obtained data using thefollowing CY Model:

${{{\eta^{*}(\omega)}} = \frac{\eta_{0}}{\left\lbrack {1 + \left( {\tau_{\eta}\omega} \right)^{a}} \right\rbrack^{\frac{({1 - n})}{a}}}},$wherein |η*(ω)| is magnitude of complex viscosity, η_(O) is zero shearviscosity, τ_(η) is viscous relaxation time, a is the breadth parameter,n is power law index, and w is angular frequency of oscillatory shear.

EXAMPLES

Bimodal catalyst system 1: consisted essentially of or made frombis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl and(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride spray-dried in a 3:1 molar ratio onto CAB-O-SIL TS610, ahydrophobic fumed silica made by surface treating hydrophilic(untreated) fumed silica with dimethyldichlorosilane support, andmethylaluminoxane (MAO), and fed into a gas phase polymerization reactoras a slurry in mineral oil. The molar ratio of moles MAO to (moles ofbis(2-pentamethylphenylamido)ethyl)amine zirconium dibenzyl +moles(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdichloride) was 140:1.

Comonomer 1: 1-Hexene, used at a molar ratio of 1-hexene/C2 in Table 1.

Ethylene (“C2”): partial pressure of C2 was maintained as describedlater in Table 1.

Inert condensing agent 1 (“ICA1”): isopentane, used at a mole percent(mol %) concentration in the gas phase of a gas phase reactor relativeto the total molar content of gas phase matter. Reported later in Table1.

Molecular hydrogen gas (“H2”): used at a molar ratio of H2/C2 in Table1.

Trim solution 1: consisted essentially of or made from(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumdimethyl (procatalyst) dissolved in heptane to give a solution having aconcentration of 0.7 gram procatalyst per milliliter solution.

Inventive Examples 1 and 2 (IE1 & IE2): synthesis of embodiments ofinventive bimodal LLDPE composition (“IE1” and “IE2”). Produced theembodiments of inventive bimodal LLDPE composition of IE1 and IE2 inseparate polymerization reaction runs in a single, continuous-mode, gasphase fluidized bed reactor. The fluidized bed reactor was configuredwith a plurality of gas feed inlets and catalyst feed inlets and aproduct discharge outlet. The polymerization reaction used BimodalCatalyst System 1, Trim solution 1, ethylene (“C2”), 1-hexene, ICA1, H₂gas. The Trim solution 1 was used to adjust the melt flow indexproperties of the embodiment of the inventive bimodal LLDPE compositionIE1. In an experimental run, the reactor was preloaded before startupwith seedbed comprising granular resin. First, the gaseous atmosphere inthe reactor containing the preloaded seedbed was dried using high purityanhydrous molecular nitrogen gas to a moisture content below 5 ppmmoisture. Then feed gases of ethylene (“C2”), 1-hexene, molecularhydrogen gas (“H2”), and ICA1 (isopentane) were introduced to build gasphase conditions in the reactor to desired operating gas phaseconditions, while the reactor was heated up to the desired operatingtemperature of 85° C. The build of gas phase conditions was performedand operating gas phase conditions were maintained in the reactor at apartial pressure of ethylene in the reactor of 1500 kPa (220 psia) andby metering the gas feeds to the reactor at a molar ratio of1-hexene/C2, a molar ratio of H2/C2, and a mole percent (mol %)isopentane as listed later in Table 1 for each example. Then mixed afeed of the Trim solution 1 with a feed of the Bimodal Catalyst System 1to give a mixture thereof, which is then fed into the reactor, whereinmixing may be done at varying molar ratios to fine tune melt index anddensity properties of bimodal LLDPE polymer being produced in thereactor to desired target values to give the embodiments of theinventive bimodal LLDPE composition (product) of IE1 and IE2. Theinventive bimodal LLDPE composition of IE1 and IE2 were collected fromthe product discharge outlet and characterized. Operating constituentsand parameters are summarized below in Table 1. Properties of theinventive bimodal LLDPE composition of IE1 and IE2 are summarized laterin Table 2. For making another embodiment of inventive bimodal LLDPEcomposition wherein density is from 0.900 to 0.920 g/cm³, replicate theprocedure except increase the molar ratio of 1-hexene/C2 from 0.038 to arange from 0.038 to 0.070. E.g., for density of 0.900 to 0.905 g/cm³,use 1-hexene/C2 molar ratio of about 0.070.

TABLE 1 (co)polymerizing conditions for Inventive Examples IE1 and IE2.Reaction Constituent/Parameter (co)polymerizing condition Reactorsingle, continuous-mode, fluidized bed Starting seedbed = granularPreloaded in reactor LDPE resin Reactor Purging method Anhydrous N₂ gasEthylene (“C2”) 1500 kPa partial pressure Comonomer = 1-hexene molarratio of 1-hexene/C2 = 0.038 (IE2) or 0.028 (IE2) Molecular hydrogen gas(“H2”) molar ratio of H2/C2 = 0.017 (IE1) or 0.018 (IE2) InertCondensing 6.6 mol % (IE1) or 8.4 mol % (IE2) Agent 1: isopentaneBimodal catalyst system 1:6070 (IE1) and 1:5450 (IE2) 1/C2 (wt/wt) TrimSolution 1/C2 (wt/wt) 1:1,310 Operating temperature 85° C. Bed weight 50kg Superficial Gas velocity 0.60 (SGV, meters/second)

TABLE 2 properties of inventive bimodal LLDPE composition of IE1 and IE2versus comparative ethylene/1-hexene LLDPE Tuflin HS 7028 NT 7 made withZiegler-Natta catalyst UCAT ™ J (CE1) and comparative ethylene/1-hexeneLLDPE Exceed 1018HA made with metallocene catalyst XCAT ™ HP (CE2),comparative ethylene/1-hexene LLDPE Alkamax ML 1810PN made withmetallocene catalyst XCAT ™ VP (CE3), all from Univation Technologies,LLC. Polymer Property Measured IE1 IE2 CE1 CE2 CE3 Density (ASTMD792-13) 0.9206 g/cm³ 0.9286 g/cm³ 0.9194 g/cm³ 0.9198 g/cm³ 0.9205g/cm³ Melt Index MI₂ (190° C., 1.11 g/10 min. 1.02 g/10 min. 1.09 g/10min. 1.03 g/10 min. 1.14 g/10 min. 2.16 kg, ASTM D1238-04) Flow IndexFI₂₁ (190° C. 32.7 g/10 min. 30.3 g/10 min. 31.3 g/10 min. 16.0 g/10min. 30.7 g/10 min. 21.6 kg, ASTM D1238-04) Melt Flow Ratio (MI₂₁/M₂)29.5 29.9 28.8 15.8 26.7 Flow Rate FR₅ (190° C., 3.24 g/10 min. 2.95g/10 min. 3.18 g/10 min. T2.58 g/10 min. 3.23 g/10 min. 5.0 kg, ASTMD1238-04) Flow Rate Ratio (FI₂₁/FR₅) 10.1 10.3 9.9 6.3 9.5 CompositionNumber-average 7,120 g/mol 5,950 g/mol 26,259 41,866 29,554 molecularweight (M_(n)) Composition Weight-average 113,400 g/mol 119,900 g/mol127,327 111,521 110,876 molecular weight (M_(w)) Composition Molecularmass 15.9 20.2 4.85 2.66 3.75 dispersity (M_(w)/M_(n)), Ð_(M) ResolvedBimodality (GPC Yes, at 4.1 Yes, at 4.1 No No No local minimum) LogMLogM LMW Polyethylene 25.2 27.5 N/applic N/applic N/applic ComponentConc. (wt %) HMW Polyethylene 74.8 72.5 N/applic N/applic N/applicComponent Conc. (wt %) LMW Polyethylene 1,970 1,763 N/applic N/applicN/applic Component M_(n) (g/mol) HMW Polyethylene 46,652 49,121 N/applicN/applic N/applic Component M_(n) (g/mol) LMW Polyethylene 4,669 4,289N/applic N/applic N/applic Component M_(w) (g/mol) HMW Polyethylene155,160 168,399 N/applic N/applic N/applic Component M_(w) (g/mol) LongChain Branching (LCB) No LCB No LCB No LCB No LCB No LCB Index detecteddetected detected detected detected Tan delta at 0.1000 radian per 9.4269.376 9.7 or 8.6 37 or 32 25 second Shear Thinning Index (1/100) 3.833.48 3.37 1.63 2.76 (SHI) Conc. = concentration. N/applic = notapplicable.

In some aspects the inventive bimodal LLDPE composition is characterizedby any one of the properties listed in Table 2, wherein the property isdefined by a range having a midpoint equal to the property value listedin Table 2 and maximum and minimum endpoints equal to, respectively,plus-or-minus (±) 55%, alternatively ±25%, alternatively ±15%,alternatively ±11%, alternatively ±5%. The resolved bimodality for IE1is shown by the GPC chromatogram in FIG. 2, wherein the peak for the LMWpolyethylene component is at approximately 3.8 LogM, the peak for theHMW polyethylene component is at approximately 4.9 LogM, and the localminimum is at approximately 4.1 LogM. The resolved bimodality for IE2 isshown by the GPC chromatogram in FIG. 3, wherein the peak for the LMWpolyethylene component is at approximately 3.7 LogM, the peak for theHMW polyethylene component is at approximately 5.1 LogM, and the localminimum is at approximately 4.1 LogM. The chromatograms in each of FIGS.2 and 3 reach baseline at approximately 2.1 LogM and approximately 6.4LogM.

Inventive Example (A) and (B) (IE(A) and IE(B)): Preparation of a 25micrometers thick, monolayer film of the inventive bimodal LLDPEcomposition of IE1 or IE2, respectively. A blown-film-line machineconfigured for making polyethylene films with a feed hopper in fluidcommunication with an extruder in heating communication with a heatingdevice heated to a temperature of 430° C. The extruder is in fluidcommunication with a die having a fixed die gap of 1.778 millimeter(70.00 mils), a blow up ratio of 2.5:1. The Frost Line Height (FLH) is81±5.1 centimeters (32±2 inches) from the die. The machine used a feedrate of inventive bimodal LLDPE composition, and production rate offilm, of 89.6 kg (197.6 pounds) per hour at a melt temperature of202°±1° C. and an extruder rate of 28.5 revolutions per minute (rpm).Properties of the film of the inventive bimodal LLDPE composition ofIE(A) (from IE1) and IE(B) (from IE2) are below in Table 3.

TABLE 3 properties of film of inventive bimodal LLDPE composition ofIE(A) and IE(B) versus comparative film of ethylene/1-hexene LLDPETuflin HS 7028 NT 7 made with Ziegler-Natta catalyst UCAT ™ J (CE(A))and comparative film of ethylene/1-hexene LLDPE Exceed 1018HA made withmetallocene catalyst XCAT ™ HP (CE(B)) or comparative film ofethylene/1-hexene LLDPE Alkamax ML 1810PN made with metallocene catalystXCAT ™ VP (CE(C)), all from Univation Technologies, LLC. PolymerProperty Measured IE(A) IE(B) CE(A) CE(B) CE(C) Dart Impact, averagedart weight 904 g 183 g 142 g 1030 g 958 g Elmendorf Tear (CD, gf) 658658 605 382 415 Elmendorf Tear (MD, gf) 339 339 384 271 313 SecantModulus (1%, CD, MPa) 286 409 208 209 262 Secant Modulus (1%, MD, MPa)239.5 374 237 215 230 Secant Modulus (2%, CD, MPa) 254.5 348 239 189 244Secant Modulus (2%, MD, MPa) 222 323 217 191 206 Tensile Strength, CDavg. strain at 10.8% 9.7% 10.5% 10.6% 9.9% yield Tensile Strength, CDavg. stress at 10.7 15.1 10.9 9.3 10.9 yield (MPa) Tensile Strength, MDavg. strain at 10.1% 9.5% 10.9% 9.98% 10.1% yield

The inventive bimodal LLDPE composition can be made into a film and theinventive bimodal LLDPE composition and film thereof has at least oneimproved property such as, for example, at least one improved(increased) processability property and/or at least one improved(increased) stiffness property. The improved processability property maybe at least one of decreased extruder barrel pressure, increasedsealability (e.g., hot seal/hot tack), decreased tan delta value, andincreased shear thinning index value. The improved stiffness propertymay be at least one of increased Elmendorf tear (CD Tear), increasedmelt strength, and increased secant modulus. In some aspects theinventive bimodal LLDPE composition is not characterized by a worseningof any three, alternatively any two, alternatively any one of theforegoing properties.

In some aspects the film of the inventive bimodal LLDPE composition ischaracterized by any one of the properties listed in Table 3 for IE(A)or IE(B), wherein the property is defined by a range having a midpointequal to the property value listed in Table 3 and maximum and minimumendpoints equal to, respectively, plus-or-minus (±) 55%, alternatively±25%, alternatively ±15%, alternatively ±11%, alternatively ±5%.

The invention claimed is:
 1. A bimodal linear low density polyethylenecomposition comprising a lower molecular weight (LMW) polyethylenecomponent and a higher molecular weight (HMW) polyethylene component,wherein each of the LMW and HMW polyethylene components comprisesethylene-derived monomeric units and (C₃-C₂₀)alpha-olefin-derivedcomonomeric units; and wherein the bimodal linear low densitypolyethylene composition is characterized by each of limitations (a) to(c): (a) a resolved bimodality showing in a chromatogram of gelpermeation chromatography (GPC) of the bimodal linear low densitypolyethylene composition, wherein the chromatogram shows a peakrepresenting the HMW polyethylene component, a peak representing the LMWpolyethylene component, and a resolved bimodal molecular weightdistribution characterized by a local minimum in a range ofLog(molecular weight) (“Log(MW)”) 4.05 to 4.25 between the peakrepresenting the HMW polyethylene component and the peak representingthe LMW polyethylene component, measured according to the BimodalityTest Method; (b) a molecular mass dispersity (M_(w)/M_(n)), Ð_(M), from5 to 30.1, measured according to the Gel Permeation Chromatography (GPC)Test Method; and (c no detectable amount of long chain branching per1,000 carbon atoms (“LCB Index”), measured according to LCB Test Method.2. The bimodal linear low density polyethylene composition of claim 1described by any one of limitations (i) to (vii): (i) a density from0.9000 to less than (<) 0.930 gram per cubic centimeter (g/cm³),measured according to ASTM D792-13 Method B; (ii) a melt index (190° C.,2.16 kilograms (kg), “MI₂”) from 0.1 to 5.0 grams per 10 minutes (g/10min.), measured according to the Melt Index MI₂ Test Method; (iii) a tandelta (tan δ) from 5 to 35, measured at 190° C. and 0.1000 radians persecond (rad/s) according to Tan Delta Test Method; (iv) both (i) and(ii); (v) both (i) and (iii); (vi) both (ii) and (iii); and (vii) eachof (i), (ii), and (iii).
 3. The bimodal linear low density polyethylenecomposition of claim 1 described by any one of limitations (i) to (vii):(i) a density from 0.9000 to less than (<) 0.930 gram per cubiccentimeter (g/cm³), measured according to ASTM D792-13 Method B; (ii) amelt index (190° C., 2.16 kilograms (kg), “MI₂”) from 0.1 to 5.0 gramsper 10 minutes (g/10 min.), measured according to the Melt Index MI₂Test Method; (iii) a molecular mass dispersity (M_(w)/M_(n)), Ð_(M), ofat least one of the LMW and HMW polyethylene components of from >2.0 to<3.0, measured according to the GPC Test Method after deconvoluting theLMW and HMW polyethylene components of the bimodal linear low densitypolyethylene composition according to the Deconvoluting Test Method;(iv) both (i) and (ii); (v) both (i) and (iii); (vi) both (ii) and(iii); and (vii) each of (i), (ii), and (iii).
 4. The bimodal linear lowdensity polyethylene composition of claim 1 described by any one oflimitations (i) to (xii): (i) a flow index (190° C., 21.6 kg, “FI₂₁”)from 4 to 500 g/10 min., measured according to the Flow Index FI₂₁ TestMethod; (ii) a melt flow ratio (190° C., “MI₂₁/MI₂”) 20.0 to 50.0, ascalculated according to the Melt Flow Ratio Test Method; (iii) a shearthinning index value from 1.5 to 10, measured according to the ShearThinning Index Test Method; (iv) a number-average molecular weight(M_(n)) from 5,000 to 25,000 grams per mole (g/mol), measured accordingto GPC Test Method; (v) both (i) and (ii); (vi) both (i) and (iii);(vii) both (i) and (iv); (viii) both (ii) and (iii); (ix) both (ii) and(iv); (x) both (iii) and (iv); (xi) any three of (i) to (iv); and (xii)each of (i) to (iv).
 5. The bimodal linear low density polyethylenecomposition of claim 1 described by any one of limitations (i) to (iv):(i) the (C₃-C₂₀)alpha-olefin-derived comonomeric units are derived from1-butene; (ii) the (C₃-C₂₀)alpha-olefin-derived comonomeric units arederived from 1-hexene; (iii) the (C₃-C₂₀)alpha-olefin-derivedcomonomeric units are derived from 1-octene; and (iv) the(C₃-C₂₀)alpha-olefin-derived comonomeric units are derived from acombination of any two, alternatively each of 1-butene, 1-hexene, and1-octene.
 6. A bimodal linear low density polyethylene composition madeby copolymerizing ethylene (monomer) and at least one(C₃-C₂₀)alpha-olefin (comonomer) with a mixture of a bimodal catalystsystem and a trim solution in the presence of molecular hydrogen gas(H₂) and an inert condensing agent (ICA) in one, two or morepolymerization reactors under (co)polymerizing conditions; wherein priorto being mixed together the trim solution consists essentially of a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconium complexand an inert liquid solvent and the bimodal catalyst system consistsessentially of an activator species, abis(2-pentamethylphenylamido)ethyl)amine zirconium complex and a(tetramethylcyclopentadienyl)(n-propylcyclopentadienyl)zirconiumcomplex, all disposed on a solid support; and wherein the(co)polymerizing conditions comprise a reaction temperature from 83degrees)(° to 87° Celsius (C.), a molar ratio of the molecular hydrogengas to the ethylene (H2/C2 molar ratio) from 0.001 to 0.050; and a molarratio of the comonomer to the ethylene (Comonomer/C2 molar ratio) from0.005 to 0.10.
 7. A manufactured article comprising a shaped form of thebimodal linear low density polyethylene composition of claim
 1. 8. Themanufactured article of claim 7 selected from: films, sheets, andinjection molded articles.
 9. The manufactured article of claim 7selected from agricultural film, food packaging, garment bags, grocerybags, heavy-duty sacks, industrial sheeting, pallet and shrink wraps,bags, buckets, freezer containers, lids, and toys.